Regarding a web rotary press having a plurality of printing units arranged ina row, various proposals have been made for a device which automatically attaches a predetermined printing plate, distributed to each fixed position of the plurality of printing units, to a predetermined position of each plate cylinder of the printing unit, and which automatically detaches the printing plate from the plate cylinder.
For example, Japanese Unexamined Patent Publication No. 74654/87 discloses a device using a robot provided with a hand having a sucking disk capable of holding a printing plate. Japanese Patent Publication No. 67023/91 shows a device comprising four interrelated base plates, coarse adjustment means provided on the first and second base plates so as to be capable of contacting and separating a printing plate with and from a predetermined position of a plate cylinder, printing plate fine adjustment means provided on the third and fourth base plates so as to be capable of properly placing a printing plate leading edge bend on a plate cylinder edge, printing plate holding means provided on the fourth base plate, means provided on the fourth base plate for bending a printing plate body along a circumferential surface of the plate cylinder, and means provided on the fourth base plate for pressing a trailing edge bend of the printing plate. Japanese Unexamined Patent Publication No. 176149/91 by the present applicant proposes a sheet-feed printing press in which a loader (cassette) capable of holding new and old printing plates is pivotably supported between printing units.
The former two devices require meticulous actions, and need a predetermined mechanism for each action. Thus, their structures have to be complicated, thereby inducing cost increases, and making the devices unreliable. The latter device, on the other hand, has a mechanism linked to a plate winding mechanism of a plate cylinder, and needs a predetermined mechanism for each action, as do the former two devices. This device also makes the structure of the loader complicated, thus involving an increased cost and prolonged actions.